Hybrid electric vehicle and method of selectively operating the hybrid electric vehicle

ABSTRACT

A series type hybrid electric vehicle that controls an internal combustion engine, generator, and electric motor for reducing the load applied to the internal combustion engine when the internal combustion engine is restarted, lowers the thermal stresses to the internal combustion engine when the engine is turned off and is able to remove excess fuel when turning off the internal combustion engine.

BACKGROUND OF THE INVENTION

[0001] 1. Field of Invention

[0002] The invention relates to methods and apparatus for adaptablycontrolling the series hybrid electric vehicle.

[0003] 2. Description of Related Art

[0004] The desire for cleaner air has caused various federal, state, andlocal governments to change their regulations to require lower vehicleemissions. Increasing urban traffic congestion has prompted a need forincreases in public mass transit services. Many large cities use busesto transport people into, out of, and within traffic congested urbanareas. Conventional buses use diesel powered internal combustionengines. Diesel engines produce emissions, including carbon monoxide,that contribute to air pollution. It is possible to refine cleanerdiesel fuel. However, cleaner diesel fuel is more costly to refine andcauses a corresponding increase in the cost of bus service.

[0005] Alternative fuels have been used to reduce emissions and conserveoil resources. Compressed natural gas has been used as an alternativefuel. Compressed natural gas does not produce as much power inconventional internal combustion engines as gasoline and diesel and hasnot been widely developed or accepted as an alternative to gasoline anddiesel.

[0006] Additives have also been developed for mixing with gasoline toreduce emissions. Ethanol and MTBE have been added to gasoline tooxygenate the combustion of gasoline and reduce emissions of carbonmonoxide. These additives, however, are believed to cause decreased gasmileage and, in the case of MTBE, to be a potential public healththreat.

[0007] Electric vehicles have been developed that produce zeroemissions. Electric vehicles are propelled by an electric motor that ispowered by a battery array on board the vehicle. The range of electricvehicles is limited as the size of the battery array which can beinstalled on the vehicle is limited. Recharging of the batteries canonly be done by connecting the battery array to a power source. Electricvehicles are not truly zero emitters when the electricity to charge thebattery array is produced by a power plant that bums, for example, coal.

[0008] Hybrid electric vehicles have also been developed to reduceemissions. Hybrid electric vehicles include an internal combustionengine and at least one electric motor powered by a battery array. In aparallel type hybrid electric vehicle, both the internal combustionengine and the electric motor are coupled to the drive train viamechanical means. The electric motor may be used to propel the vehicleat low speeds and to assist the internal combustion engine at higherspeeds. The electric motor may also be driven, in part, by the internalcombustion engine and be operated as a generator to recharge the batteryarray.

[0009] In a series type hybrid electric vehicle, the internal combustionengine is used only to run a generator that charges the battery array.There is no mechanical connection of the internal combustion engine tothe vehicle drive train. The electric traction drive motor is powered bythe battery array and is mechanically connected to the vehicle drivetrain.

[0010] In present series type hybrid electric vehicles, there is a needto control the engine, generator and electric motor according to theemission environment. In one emission environment, the engine is runningat a selected operating speed. However, in a second emissionenvironment, the engine is turned off. There is thus a need to controlthis engine, generator and electric motor to reduce engine wear duringengine start up as the engine operates in the various operating modes.There is also a need to control the engine, generator and electric motorto reduce engine wear of the engine and to remove excess fuel duringengine shut off.

SUMMARY OF THE INVENTION

[0011] The invention provides methods and apparatus for adaptivelymanaging the internal combustion engine, generator, and electric motorfor a series type hybrid electric vehicle.

[0012] An exemplary embodiment of a series type hybrid electric vehicleaccording to the invention is controlled so that a generator set of thevehicle, including an internal combustion engine connected to agenerator, reduces the load applied to the internal combustion enginewhen the internal combustion engine is restarted, lowers the thermalstresses to the internal combustion engine when the engine is turned offand is able to remove excess fuel when turning off the internalcombustion engine.

[0013] According to an exemplary embodiment, a method for adaptivelycontrolling the state of charge of a battery array of a series typehybrid electric vehicle having an internal combustion engine connectedto a generator and at least one electric motor with the internalcombustion engine and generator selectively operated in variousoperation modes consisting of operating the vehicle in a first mode inwhich the internal combustion engine and generator are off and the motorpropels the vehicle from power stored in the battery array, operatingthe vehicle in a second mode in which the internal combustion engine andgenerator are operating without restriction, and operating the vehiclein a third mode in which the operation of the internal combustion engineand generator are at least partially restricted to limit vehicledischarges.

[0014] According to another exemplary embodiment, a series type hybridelectric vehicle includes an internal combustion engine connected to agenerator, a battery array receiving current at least from thegenerator, at least one electric motor receiving current from thebattery array, and a controller that selectively operates the engine andgenerator in various operating modes, including a first mode in whichthe internal combustion engine and generator are off and the motorpropels the vehicle from power stored in the battery array, a secondmode in which the internal combustion engine and generator are operatingwithout restriction, and a third mode in which the operation of theinternal combustion engine and generator are at least partiallyrestricted to limit vehicle discharges.

[0015] Other features of the invention will become apparent as thefollowing description proceeds and upon reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Various exemplary embodiments of this invention will be describedin detail with reference to the following figures, wherein like numeralsreference like elements, and wherein:

[0017]FIG. 1 is schematic view of an exemplary embodiment of a serieshybrid electric vehicle according to the invention;

[0018]FIG. 2 is a schematic diagram illustrating an exemplary embodimentof a circuit for controlling charging of the battery array by thegenerator;

[0019]FIG. 3 is a diagram illustrating an exemplary embodiment of acircuit for controlling the electric motors;

[0020]FIG. 4 is a diagram illustrating an exemplary embodiment of acircuit of the motor controllers;

[0021]FIG. 5 is a diagram illustrating an exemplary embodiment of amaster control switch;

[0022]FIG. 6 is a diagram illustrating an exemplary embodiment of adriver's input control panel;

[0023]FIG. 7 is a diagram illustrating the relationship between thepower created, the power stored, and the power consumed by the serieshybrid electric vehicle;

[0024] FIGS. 8-11 are flowcharts illustrating an exemplary control ofthe series hybrid electric vehicle.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0025] Referring to FIG. 1, an exemplary embodiment of a series typehybrid electric vehicle 10 according to the invention includes aplurality of wheels 11, 12, 13, and 14 and a vehicle chassis 15. Thewheels 13 and 14 are coupled to electric motors 50 and 60, respectively,through gear boxes 52 and 62, respectively. The wheels 13 and 14 areindependently mounted to respective suspension components, such as swingarms. In this embodiment, the wheels 13 and 14 are not coupled togetherby an axle. In other embodiments, the wheels 13 and 14 may be coupledtogether, for example, by an axle. The wheels 13 and 14 may be eitherthe front wheels or the rear wheels of the vehicle 10. In thisembodiment, the wheels 11 and 12 are not driven and may be coupledtogether by an axle. In other embodiments, the wheels 11 and 12 may alsobe driven.

[0026] In an exemplary embodiment of the vehicle according to theinvention, the vehicle 10 is a bus having an occupancy capacity inexcess of 100. However, it should be appreciated that the vehicle may bea bus of a smaller capacity or that the vehicle may be a smallerpassenger vehicle, such as a sedan. In various exemplary embodiments,the vehicle may be any size and form currently used or later developed.

[0027] The electric motors 50 and 60 are powered by a battery array 30and are controlled by motor controllers 51 and 61, respectively.According to an exemplary embodiment of the vehicle 10, the electricmotors 50 and 60 are synchronous, permanent magnet DC brushless motors.Each electric motor 50 and 60 is rated for 220 Hp and 0-11,000 rpm. Themaximum combined power output of the electric motors 50 and 60 is thus440 Hp. The permanent magnet DC brushless motors include permanentmagnets, such as rare earth magnets, for providing a magnetic field asopposed to AC induction motors which create or induce a magnetic fieldon the rotating portion of the motor. The DC brushless motors are thusinherently more efficient than AC induction motors as no losses occurfrom inducing the magnetic field. The DC brushless motors also have amore useful torque profile, a smaller form factor, and lower weight thanAC induction motors. The DC brushless motors also require less energyinput for an equivalent power output than AC induction motors. However,this invention is not limited to permanent magnet DC brushless motors,and other types of electric motors, such as AC induction motors, can beused.

[0028] The series type hybrid electric vehicle 10 also includes agenerator set (genset) 300, 310 including an internal combustion engine300 and a generator 310 that is driven by the internal combustion engine300. The internal combustion engine 300 may be powered by gasoline,diesel, or compressed natural gas. It should be appreciated, however,that the internal combustion engine 300 may be replaced by a fuel cell,turbine or any other number of alternatives for creating usable electricpower. According to an exemplary embodiment of the invention, theinternal combustion engine 300 may be a 2.5 liter Ford LRG-425 enginepowered by compressed natural gas. The engine 300 is operated to produce70 Hp. It should be appreciated that the power of the engine 300 may beincreased by increasing the RPM of the engine 300 and decreased bydecreasing the RPM of the engine 300. In this embodiment with two 220 Hpelectric motors 50 and 60 and an internal combustion engine 300operating at 70 Hp, the performance enhancement factor of the vehicle 10is 440/70, or at least 6.2. Other internal combustion engines can ofcourse be utilized.

[0029] The generator 310 is a DC brushless generator that produces, forexample, 240-400 V_(AC). In an exemplary embodiment of the vehicle 10,the generator is operated to produce 345 V_(AC) during certain drivemodes. An output shaft of the internal combustion engine 300 isconnected to the generator 310 and the AC voltage of the generator 310is converted to a DC voltage by a generator controller 320. Theconverted DC voltage charges the battery array 30. The battery array mayinclude, for example, 26 deep cycle, lead-acid batteries of 12 voltseach connected in series. It should be appreciated, however, that otherbatteries, such as nickel cadmium, metal hydride or lithium ion, may beused and that any number of batteries can be employed, as space permits.Depending upon the load on the vehicle 10, the battery array voltageranges between 240 and 400 V_(DC).

[0030] An electronic control unit (ECU) 200 includes a programmablelogic controller (PLC) 210 and a master control panel (MCP) 220. The MCP220 receives input from various sensors and provides the connection tooutputs in the vehicle 10 regarding the information received from thesensors. Some or all of the information is provided to the PLC 210. ThePLC 210 executes various programs to control, for example, the internalcombustion engine 300, the generator 310, the generator controller 320,the electric motors 50 and 60, and the motor controllers 51 and 61,based in part on information received from the MCP 220.

[0031] Although not shown in the drawings, the vehicle 10 includes acooling system or cooling systems for the internal combustion engine300, the generator controller 320, the battery array 30, and the motorcontrollers 51 and 61. The cooling system may be a single system whichincludes a coolant reservoir, a pump for pumping the coolant through aheat exchanger such as a radiator and a fan for moving air across theheat exchanger or a plurality of cooling systems similarly constructed.The ECU 200 controls the cooling systems, including the pumps and thefans, to perform a heat shedding operation in which the heat generatedby the engine 300, the controllers 320, 51, and 61, the battery array30, and various other systems is released to the atmosphere. Anyacceptable means and methods for cooling the vehicle components may beutilized.

[0032] As shown in FIG. 2, the coils of the generator 310 are connectedto the generator controller 320. The generator controller 320 includestwo switching insulated or isolated gate bipolar transistors (IGBT) 330per phase of the generator 310 and their corresponding diodes. In anexemplary embodiment including a three phase generator 310, thegenerator controller includes 6 IGBT 330. The PLC 210 controls each IGBT330 of the generator controller 320 to control the conversion of the ACvoltage of the generator 310 to the DC voltage for charging the batteryarray 30. The PLC 210 may switch the IGBT 330 off when the SOC of thebattery array 30 reaches an upper control limit to stop the conversionof the AC voltage to DC voltage and prevent overcharging of the batteryarray 30.

[0033] According to an exemplary embodiment of the invention, the engine300 runs continuously during operation of the vehicle 10 andcontinuously turns the shaft of the generator 310. The PLC 210 switcheseach IGBT 330 on and off via high speed pulse width modulation (PWM) tocontrol charging of the battery array 30. It should be appreciatedhowever that the PLC 210 may control the engine 300 by turning theengine 300 on and off to control charging of the battery array 30.

[0034] Referring to FIG. 3, a control circuit for the electric motors 50and 60 includes the motor controllers 51 and 61. The motor controllers51 and 61 receive power from the battery array 30 and distribute thepower to the electric motors 50 and 60 by switches B1-B6 of pulse widthmodulation (PWM) inverters 54 and 64. The PWM inverters 54 and 64generate AC current from the DC battery array 30. The battery currentI_(B) is distributed by the switches B1-B6, for example IGBT, of the PWMinverters 54 and 64 into motor currents I₁, I₂, and I₃ for driving themotors 50 and 60. The motor controllers 51 and 61 distribute the batterycurrent IB via the switches B1-B6 by factoring feedback from positionsensors 53 and 63 and encoders 56 and 66 that determine the timing orpulsing of electromagnets of the motors 50 and 60. The pole positionsensors 53 and 63 determine the pole positions of the permanent magnetsof the motors 50 and 60 and the encoders 56 and 66 determine the phaseangle. It should be appreciated that each pair of pole position sensors53 and 63 and encoders 56 and 66, respectively, may be replaced by aphase position sensor and the phase change frequency may be read todetermine the speed of rotation of the electric motors 50 and 60.

[0035] The motor controllers 51 and 61 calculate the motor connectorvoltages U₁₂, U₁₃, and U₂₃ based on the rotary velocity and the knownflux value of the motors 50 and 60 between the motor connectors. Theoperation of the inverters 54 and 64 is then determined by the rectifiedvoltages of the diodes of the switches B1-B6 or by the voltage Ui of anintermediate circuit including a capacitor C. If the voltage Ui becomeslarger than the battery voltage U_(B), uncontrolled current may flow tothe battery array 30. Voltage sensors 55 and 65 determine the voltage Uiand the motor controllers 51 and 61 compare the voltage Ui to thebattery voltage U_(B). If Ui is greater than U_(B), the motorcontrollers 51 and 61 activate the switches B1-B6 to cause magnetizingcurrent to flow to the motors 50 and 60 to avoid unnecessary rechargingof the battery array 30.

[0036] As shown in FIG. 3, each motor controller 51 and 61 receivescontrol data from the ECU 200 through a controller area network (CAN).The ECU 200 can communicate with the various sensors and the motorcontrollers 51 and 61 by, for example, DeviceNet™, an open, globalindustry standard communication network.

[0037] Referring to FIG. 4, each motor controller 51 and 61 includes acontrol unit 101 which includes a field axis current and torque axiscurrent detector 102, a field axis current and torque axis currentcontrol unit 103, a field axis current reference control unit 104, atorque axis current reference control unit 105, an rpm calculator 106, a2/3 phase changer 107, a phase calculator 108 and a PWM control unit109.

[0038] The detector 102 calculates the torque axis current I_(t) and thefield axis current I_(f) by executing a 3-phase, 2-phase coordinatetransfer from the input of (1) current detectors 57 and 67 that measurethe 3-phase AC current of the motors 50 and 60 and (2) phase calculator108 that receives input from the position sensors 53 and 63 and theencoders 56 and 66. The field axis current I_(f) is a measure of thecurrent used for winding the motor and the torque axis current I_(t) isa measure of the back electric current in maintaining the synchronizedrotation of the motors 50 and 60 when the rotation of the motors 50 and60 is reduced.

[0039] The output of detector 102 goes to the field axis current andtorque axis current control unit 103. The current control unit 103 alsoreceives (1) a field axis current reference value I_(fref) from thefield axis current reference control unit 104 and (2) a torque axiscurrent reference value I_(tref) from the torque axis current referencecontrol unit 105.

[0040] The reference control units 104 and 105 determine the currentreference values I_(fref) and I_(tref) by comparing a torque referencevalue T_(ref) (which is determined by the position of an acceleratorpedal of the vehicle) with the actual rotational velocity determined bythe rpm calculator 106 that receives input from the encoders 56 and 66.

[0041] The 2/3 phase changer 107 receives input from the current controlunit 103 and the phase calculator 108, and calculates the 3-phase ACreference values by performing a 2-phase/3-phase coordinatetransformation. The PWM control unit 109 generates a PWM signal bycomparing the 3-phase reference values received from the 2/3 phasechanger 107 with a triangular wave signal. The PWM control unit 109communicates this PWM signal to the PWM inverters 54 and 64.

[0042] Referring to FIG. 5, a master control switch 20 positioned, forexample, in an operator area of the vehicle 10, includes an offposition, a drive enable position and an engine run position. Anyacceptable switch mechanism can be employed. The rotary switch 20 inFIG. 5 is merely an example of an acceptable switch. The position of theswitch 20 is input to the MCP 220. When the switch 20 is moved to thedrive enable position, the PLC 210 controls the electric motors 50 and60 to run the vehicle in a driver selected zero emissions mode bydrawing power from the battery array 30, i.e., the electric motors 50and 60 are powered solely by the battery array 30. The genset 300, 310is not operated during the zero emissions mode. The range of the vehicle10 in zero emissions mode is limited as the state of charge (SOC), i.e.,the amount of energy stored within a battery, of the battery array 30will eventually be lowered below a level sufficient to drive theelectric motors 50 and 60 to propel the vehicle.

[0043] When the switch 20 is moved to the engine run position, the ECU200 instructs the generator 310 to operate as a motor for starting theengine 300. During the starting of the engine 300, the generator 310receives current from the battery array 30. The current is supplieduntil the engine 300 reaches a predetermined idling speed and then thecurrent supply is stopped. The engine 300 then drives the generator 310to charge the battery array 30, as necessary. The ECU 200 controls theengine 300 by monitoring the engine speed (rpm) as sensed by atachometer (not shown) and the fuel mixture as sensed by an oxygensensor (not shown). The ECU 200 may, for example, control a fuelinjection amount of the engine 300 and/or the position of a throttlevalve of the engine 300. The ECU 200 may also monitor engine conditionssuch as the oil pressure and the coolant temperature as detected bysensors (not shown). An automatic zero emission mode is provided by theECU 200 while in the engine run position when the SOC of the batteryarray 30 is sufficient or when the sensors of the vehicle 10 sense areasand routes where zero emission modes are required.

[0044] Referring to FIG. 6, a control panel 25 positioned, for example,in the operator area of the vehicle 10, includes a plurality of switches26-29. After starting the vehicle 10 by moving the master switch 20 tothe engine run position, one of the switches 26-29 is selected toestablish a driving mode of the vehicle 10. A first driving mode F1 isestablished by selecting switch 26. The first driving mode F1 isestablished for driving the vehicle at lower speeds under conditions inwhich the vehicle 10 will start and stop frequently. A second drivingmode F2 is established by selecting switch 27. The second driving modeF2 is established for driving the vehicle at higher speeds and underconditions in which the vehicle is started and stopped less frequently.The ECU 200 controls the electric motors 50 and 60 depending on whichdriving mode is established. The maximum power output and rpm of theelectric motors 50 and 60 in the second driving mode F2 are higher thanthe maximum power output and rpm of the motors 50 and 60 in the firstdriving mode F1.

[0045] While two driving modes are shown, any number of modes can beused, depending on the driving conditions, road conditions, weatherconditions, and the like.

[0046] The control panel 25 also includes a switch 28 to establish aneutral mode N. In the neutral mode N, the electric motors 50 and 60 aredisengaged by the ECU 200. A reverse mode R is established by selectinga switch 29. In the reverse mode R, the electric motors 50 and 60 arecontrolled to rotate in the opposite direction of the first and seconddriving modes F1 and F2.

[0047] Referring to FIG. 7, the relationship between the powergenerated, the power stored, and the power consumed over time, by theseries hybrid electric vehicle 10 according to the invention will beexplained.

[0048] Power is consumed from the battery array 30 by the electricmotors 50 and 60 during acceleration of the vehicle 10 to a cruisingspeed. As shown in FIG. 7, the vehicle 10 reaches cruising speed at timet₁ which corresponds to a peak power P_(peak) of the electric motors 50and 60. The peak power P_(peak) of the electric motors 50 and 60 isdependent on the driving mode of the vehicle 10 selected by theoperator. In the exemplary embodiment of the invention in which theelectric motors 50 and 60 are each 220 Hp, the peak power P_(peak)consumed by the electric motors 50 and 60 is 440 Hp.

[0049] The power consumption (traction effort) of the electric motors 50and 60 during acceleration is represented by the curve below thehorizontal axis and the area defined by the curve below the horizontalaxis between the times t₀ and t₂ represents the total power consumptionof the vehicle 10 during acceleration. In the event that the SOC of thebattery array 30 is insufficient to achieve the cruising speed, the ECU200 controls the motor controllers 51 and 61 to limit the peak powerP_(peak) the electric motors 50 and 60 may draw from the battery array30. After the vehicle 10 has accelerated to cruising speed, the tractioneffort of the electric motors 50 and 60 may be reduced between the timet₁ and a time t₂ and the power consumption by the electric motors 50 and60 may also be reduced.

[0050] The cruising speed of the vehicle 10 is maintained between thetime t₂ and a time t₃. During the time between t₂ and t₃, the genset300, 310 is operated to produce power P_(gen) higher than the powerconsumption (traction effort) of the electric motors 50 and 60 necessaryto maintain the vehicle's cruising speed. The differential in powerbetween the traction effort and the power generated P_(gen) is stored inthe battery array 30.

[0051] The power P_(gen) generated by the genset 300, 310 is dependenton the rpm of the engine 300 and a user demand signal sent to the genset300, 310 that is controlled by the ECU 200. The ECU 200 controls theengine 300 to generally maintain the rpm of the engine 300, and thepower generated P_(gen), constant. However, it should be appreciatedthat the ECU 200 may control the engine 300 to reduce or increase therpm of the engine 300, and thus the reduce or increase, respectively,the power generated P_(gen).

[0052] The power generated P_(gen) by the genset 300, 310 may be reducedif the SOC of the battery array 30 approaches an upper control limit atwhich the battery array 30 may become overcharged. The power generatedP_(gen) by the genset 300, 310 may be increased if the SOC of thebattery array 30 approaches a lower control limit at which the batteryarray 30 would be unable to drive the electric motors 50 and 60 withenough torque to propel the vehicle 10. In an exemplary embodiment ofthe vehicle 10 in which the engine 300 is a 2.5 liter Ford LRG-425engine powered by compressed natural gas, the power generated P_(gen) is70 Hp.

[0053] Regenerative braking occurs between the times t₃ and t₄ when thevehicle 10 decelerates after release of the accelerator pedal and whenthe vehicle 10 travels on a downhill slope at a constant speed. Duringregenerative braking, the electric motors 50 and 60 function asgenerators and current is supplied to the battery array 30 by theelectric motors 50 and 60. The power generated P_(braking) duringregenerative braking is stored in the battery array 30.

[0054] The power generated by the genset 300, 310 during maintenance ofthe cruising speed and the power generated by regenerative brakingP_(braking) is represented by the curve above the horizontal axis andthe area defined by the curve above the horizontal axis represents thetotal energy creation and storage of the vehicle 10 during maintenanceof the cruising speed and regenerative braking.

[0055] The power P_(gen) of the genset 300, 310 and the regenerativebraking power P_(braking) are controlled by the ECU 200 to substantiallyequal the energy consumption (traction effort) of the electric motors 50and 60 during acceleration. In other words, the area defined by thecurve below the horizontal axis is equal to the area defined by thecurve above the horizontal axis. The ECU 200 controls the tractioneffort of the electric motors 50 and 60 (including the peak powerP_(peak)) and the power generated P_(gen) so that the power generatedand the power stored do not exceed the power consumed, and vice versa,so as to maintain the SOC of the battery array 30 within a range ofcontrol limits. The ECU 200 controls the power generated P_(gen) and thetraction effort of the electric motors 50 and 60 so that the amperehours during energy consumption do not exceed the thermal capacity ofthe battery array during power creation and storage.

[0056] As discussed above, in certain operational modes, the genset 300,310 operates to produce power higher than the power consumption of theelectric motors 50 and 60. In various exemplary embodiments, the poweroutput by the genset 300, 310 declines as the SOC of the battery array30 approaches a high level SOC. The battery array 30 is not fullycharged, but managed to a SOC level predetermined to maximize thebattery life and to accommodate the power requirements of the electricmotors 50 and 60. Thus, it should be appreciated that the battery array30 can be maintained at any SOC level less than the maximum SOC level.By keeping the battery array 30 at less than the maximum SOC, thebattery array 30 is less likely to experience thermal runaway due toovercharging.

[0057] Furthermore, the MCP 220 can determine the SOC of the batteryarray 30 over a period of time to determine if there are any trends inthe SOC level. The trend can be an overall reduction, increase, ormaintaining of the SOC of the battery array 30 over a predeterminedperiod of time. The MCP 220 can determine an accurate trend because therequired energy by the genset 300, 310 does not vary greatly since thegenset 300, 310 does not directly drive the vehicle 10. The MCP 220 canthus readily determine the trend, and the PLC 210 can adjust the energyrequirement of the genset 300, 310 accordingly.

[0058] The vehicle 10, in this exemplary embodiment, has three modes ofoperation, a zero emissions mode 3, a limited emissions mode 2, and afull emissions mode 1. It should be appreciated that more than threeemission modes can be provided, depending, perhaps, on the differentenvironments in which a particular vehicle 10 will be used.

[0059] Zero emission mode 3 refers to the mode of operation of thevehicle 10 in which there are substantially no atmospheric, noise,thermal, or other discharges. It may be desirable for vehicle 10 tooperate in the zero emission mode when it is in or adjacent a buildingor other area with limited air flow or in an area where exhaust gasescause a public health concern.

[0060] For example, one type of environment in which the vehicle 10 maybe operated is in a closed route or circuit such as at an airport or aconfined shopping area where the vehicle 10 travels the same circuitcontinuously. At certain locations in the circuit, it may be desirablefor the vehicle 10 to emit zero emissions. For example, at an airport,it is desirable that the vehicle emit zero emissions when it is in orimmediately adjacent a terminal, a rental car facility, a parkinggarage, etc., i.e., any time the vehicle 10 is in or adjacent a facilitywith limited air flow or circulation.

[0061] These zero emission environments may not be limited to buildings.It may be desirable for the vehicle 10 to operate at zero emissions evenwhen the vehicle is in an open-air environment if public health is aconcern, for example, next to a hospital or other medical facility, inan area where vehicle emissions are of a great concern, etc.

[0062] Vehicle 10 may, of course, be operated in any environment, andits course may vary, i.e., the vehicle 10 may be operated over openroads, without being restricted to a particular circuit or route.

[0063] The intermediate emission mode 2 refers to the mode of operationof the vehicle 10 in which certain or all discharges are restricted orlimited. The genset 300, 310 does not run at a full operational level inthe intermediate emission mode 2. One type of environment in which thevehicle 10 may be operated in the intermediate emission mode 2 may be anarea bordering a zero emission zone. Also there may be certainenvironments where certain emissions are prohibited or limited, e.g., alimit on the amount of exhaust gases which are allowed in a particulararea for public health reasons, while other discharges (e.g., noise) arenot restricted.

[0064] The full emission mode 1 refers to the mode of operation of thevehicle 10 in which the operation of the vehicle 10 is not restricted byany emissions limitations or restrictions. Thus, the genset 300, 310 canoperate at the full operational level without restriction.

[0065] An exemplary embodiment for controlling the series type hybridelectric vehicle 10 will be explained with reference to FIGS. 8-11. Thecontrol method shown in FIGS. 8-11 may be automatically executed atpredetermined times or locations during operation of the vehicle 10, orexecuted manually.

[0066] The control method begins at step S100 and proceeds to step S110where the MCP 220 determines the emission mode in which vehicle 10should be operating.

[0067] The emission mode in which the vehicle 10 should be operating maybe automatically determined by sensors on the vehicle 10, e.g., a GPS,radio, mechanical trip, mileage counter, etc. mounted on the vehicle 10which may interact with transmitters along the route traversed by thevehicle 10. It should be appreciated that any automatic means currentlyavailable or later developed can be used for the vehicle 10 to determinethe location of the vehicle 10, and thus determine what emission modethe vehicle 10 should be in. Also, a visible (e.g., a sign) or anaudible signal mechanism could signal to the driver as to the mode thevehicle 10 should be operating in, and the driver could supply thisinformation to the MCP 220.

[0068] The control method then proceeds to step S120 where it isdetermined if the vehicle is in emission mode 1. If the vehicle is inemission mode 1 (S120:Yes), the control method proceeds to step S300(see FIG. 9). If the vehicle is not in emission mode 1 (S120:No), thecontrol method proceeds to step S130 where it is determined if thevehicle 10 is in emission mode 2. If the vehicle is in emission mode 2(S130:Yes), the control method also proceeds to step S300.

[0069] If the MCP 220 determines that the vehicle 10 is not in emissionmode 2 (S130:No), the control method proceeds to step 140 where it isdetermined if the vehicle is in emission mode 3. If the vehicle 10 isnot in emission mode 3 (S140:No), the control method returns to stepS110 where the MCP 220 again determines what emission mode the vehicle10 is in. If the vehicle 10 is in emission mode 3 (S140:Yes), thecontrol method proceeds to step S500, which is discussed below.

[0070] When the control method proceeds to step S300 (see FIG. 9), theMCP 220 has determined that the vehicle 10 should be operating in eitheremission mode 1 or emission mode 2. The MCP 220 receives input from asensor indicating if the internal combustion engine 300 is on. If theinternal combustion 300 is on (S330:Yes), the method proceeds to stepS400. If the internal combustion engine 300 is off (S300:No), thecontrol method proceeds to step S310 where the PLC 210 instructs thegenerator 310 to operate as a motor for starting the internal combustionengine 300. The PLC 210 also activates an oil pump to increase the oilpressure in the internal combustion engine 300 before it is started bygenerator 310. In various exemplary embodiments, the pump is anauxiliary oil pump attached to the generator 310. Thus, as the PLC 210turns on the genset 300, 310, the generator 310 also turns on the oilpump. In various exemplary embodiments, when the internal combustionengine 300 is a large engine, an additional pump can also be provided topump oil into the internal combustion engine 300. In this exemplaryembodiment, the additional electrical pump can be a separate pump, whichis not attached to the internal combustion engine.

[0071] The control method then proceeds to step S320 where the MCP 220receives input from a sensor indicating the oil pressure X within theinternal combustion engine 300. The MCP 220 determines if the oilpressure X is equal to or greater than a predetermined oil pressure X1.The predetermined oil pressure X1 is the oil pressure which assures thatoil is adequately supplied to the internal combustion engine 300. Invarious exemplary embodiments, if the internal combustion engine 300 isa 2.5 liter Ford LRG-425 engine, the predetermined oil pressure could beapproximately 40 psi. However, it should be appreciated that other oilpressures may be acceptable, depending on the types of engine and theoperating conditions of the engines.

[0072] If the MCP 220 determines that the oil pressure X is less thanthe predetermined oil pressure X1 (S320:No), the control method returnsto step S310. If the oil pressure is equal to or greater than thepredetermined oil pressure X1, the control method proceeds to step S330where the PLC 220 instructs the internal combustion engine 300 to startapplying an ignition spark. The control method then proceeds to stepS340 where the MCP 220 receives input from a sensor indicating whetherthe spark has been stabilized. If the spark has not been stabilized(S340:No), the control method returns to step S330 where the ignitionspark is applied again.

[0073] If, however, the MCP 220 determines that a stable spark has beenachieved, (S340:Yes), the control method proceeds to step S350 wherefuel is supplied to the internal combustion engine 300.

[0074] The control method then proceeds to step S360 where the MCP 220receives input from a sensor indicating if the engine 300 has achieved astable idle. A stable idle ignition has been achieved when the MCP 220determines that the internal combustion engine 300 is able to operatewithout the use of the generator 310 as a motor. This is normallydetermined by comparing the rotation of the internal combustion engine300 with a predetermined rotation, with the predetermined rotation beinga rotation at which the engine 300 can sustain operation.

[0075] If the rotation of the internal combustion engine 300 is notabove the predetermined rotation at step 360 (S360:No), the controlmethod returns to step S350 where more fuel is supplied to the internalcombustion engine 300. If, however, the internal combustion engine 300is above a predetermined rotation (S360:Yes), the control methodproceeds to step S370 and the PLC 210 instructs the generator 310 tostop operating as a motor for starting the internal combustion engine300. At this point, the internal combustion engine 300 is able tooperate (rotate) without the assistance of the generator 310.

[0076] As should be appreciated, this control method and apparatusavoids the application of a large mechanical load to the internalcombustion engine 300 upon starting, because a sufficient oil pressureis attained before the spark and fuel are supplied. The oil pressurereduces the mechanical load as a sufficient amount of oil creates asmooth transition in restarting the rotation of the internal combustionengine 300. Thus, the restarting of the genset 300, 310 only has towithstand a relatively low load from the starting of the generator 310and not a large load from the starting of the internal combustion engine300.

[0077] After the generator 310 ceases functioning as a starter motor instep S370, the control method proceeds to step S380 where the MCP 220receives input from a sensor to determine if the temperature H of thegenset 300, 310 is equal to or above a predetermined temperature H1. Thepredetermined temperature H1 is the desired thermal level for operatingthe genset 300, 310 at full output.

[0078] If the temperature H is less than the predetermined temperatureH1 (S380:No), the control method proceeds to step S390 where the PLC 210instructs the genset 300, 310 to move to an idle warm up phase.

[0079] As should be appreciated, the generator 310 usually reaches anappropriate thermal level to sustain full output faster than theinternal combustion engine 300. If the generator reaches an appropriatethermal level before the internal combustion engine 300, the PLC 210stops the idle-warm up phase for the generator 310 and the generatorremains idle, while the engine 200 is still being heated, until the MCP220 receives input from a sensor associated with the internal combustionengine 300 to indicate that the internal combustion engine has reachedan appropriate thermal level to sustain full output. However, in variousexemplary embodiments, the PLC 210 can increase the rate to thermallywarm the internal combustion engine 300, as determined by the MCP 220based on data from sensors, so that both the internal combustion engine300 and generator 310 reach the appropriate thermal level atsubstantially the same time. In the alternative, the PLC 210 candecrease the rate at which the generator 310 is being heated, based ondata from sensors, so that both the internal combustion engine 300 andgenerator 310 reach the appropriate thermal level at substantially thesame time.

[0080] Once the temperature of the genset 300, 310 is equal to orgreater than the predetermined temperature H1 (S380:Yes) the controlmethod proceeds to step S400 where the MCP 220, as described above, hasautomatically determined the emission mode in which the vehicle 10should be operating.

[0081] If the vehicle 10 should be in emission mode 1 (S400:Yes), thecontrol method proceeds to step S420 where the power output by thegenset 300, 310 can be maximized. The power output by the genset 300,310 can be maximized as the P_(gen) by the generator 310 can beincreased to the current rotation of the internal combustion engine 300and the rotational speed of the internal combustion engine 300 can beincreased to its maximum rotation. However, if the battery array 300 isalready charged to the desired SOC, the genset 300, 310 could go to anormal operation or any other operation to maintain a predetermined SOCof the battery array 30. It should be appreciated that it could bedesirable for the genset 300, 310 to be operating at fill maximum poweroutput when the SOC of the battery array 30 is at a low SOC, if a highpower output is required to operate the auxiliary systems of thevehicle, if different routes and/or different times of day vary theaverage power demands for the battery array 30, or any other situationthat would require a rapid charging of the battery array 30.

[0082] If the MCP 220 determines that the vehicle 10 is in emission mode2 (S400:No), the control method proceeds to step S410 where the poweroutput by the genset 300, 310 is minimized. The power output of thegenset 300, 310 is minimized based on the emission limitations of theenvironment in which the vehicle 10 is operating. Thus, the genset 300,310 can operate to produce power less than the maximum output, buthigher than the power consumption of the electric motors 50 and 60, atthe same level as the power consumption of the electric motors 50 and60, or below the power consumption of the electric motors 50 and 60 toreduce the drain on the electrical charge of the battery array 30 to alower control limit. While a single intermediate mode has beenexplained, it should be appreciated that the intermediate mode can haveseveral sub-levels, meeting various emission limitations orrestrictions. Thus, the allowable power output by the genset 300, 310may vary based on the environment in which vehicle 10 is operating, andmay vary at many different levels.

[0083] In various exemplary embodiments, when the internal combustionengine 300 is turned on in step S410 and step S420, the PLC 210gradually increases the rotational speed of the internal combustionengine 300. The PLC 210 gradually increases the rotational speed, ratherthan immediately starting the normal operation of the internalcombustion engine 300, to further lessen the engine load when startingthe internal combustion engine 300.

[0084] After vehicle 10 is fully operational in modes 2 or 3, i.e., thevehicle 10 is operating in its normal mode, as discussed above, thecontrol method proceeds to step S200 (see FIG. 11). In step S200, theMCP again receives input from a sensor which measures the energy outputE of genset 300, 310, and compares E to a predetermined energy level E1.

[0085] If the energy level E is above a predetermined energy level E1(S200:Yes), control method proceeds to step S210 where the PLC 210either reduces the rotation of the internal combustion engine 300,changes the position of the throttle valve of the internal combustionengine 300 to reduce the fuel to engine 300, and/or applies a retarderto slow down the power output of the internal combustion engine 300.

[0086] The control method then proceeds to step S220 where the PLC 210instructs the genset 300, 310 to operate as indicated in step S210 toburn off the excess energy through the internal combustion engine 300.Thus, excess energy is burned off to reduce the energy level E.

[0087] The control method then proceeds to step S230 where the MCP 220receives input from a sensor to determine if the energy level E is lessthan the predetermined energy level E1. If the energy level is greaterthan or equal to the predetermined energy level E1 (S230:Yes), thecontrol method returns to step S210. If the energy level E is less thanor equal to the predetermined energy level E1 (S230:No), the controlmethod proceeds to step S250 where the control method ends.

[0088] As stated above, when vehicle 10 is in emission mode 3(S140:Yes), the control method goes to step S500 (see FIG. 10). In stepS500, the MCP 220 receives input from a sensor to determine if theinternal combustion engine 300 is on. If the internal combustion engineis off (S500:Yes), the control method proceeds to step S250, where thecontrol method ends.

[0089] If the MCP 220 determines that the engine is on (S500:No), thecontrol method proceeds to step S510 where the PLC 210 switches theinternal combustion engine 300 from a power generation mode to an engineidle mode. Thus, the internal combustion engine 300 stops driving thegenerator 310.

[0090] The control method then proceeds to step S520 where the PLC 210activates the cooling system to thermally cool the internal combustionengine 300. The control method then proceeds to step S530 where thetemperature H of the internal combustion engine 300 is compared to apredetermined temperature H2. The predetermined temperature H2 is apredetermined temperature used to prevent thermal shock and a heat soakeffect before turning off the internal combustion engine 300. The heatsoak effect occurs when particular sections of the internal combustionengine 300 are warmer than other sections, with the warmer sections thuswarming the entire internal combustion engine. By uniformly cooling theinternal combustion engine 300, the structural integrity of the enginecan be maintained because the engine is able to adequately cool to apredetermined temperature H2.

[0091] If the temperature H of the internal combustion engine 300 isgreater than the predetermined temperature H2 (S530:Yes), the controlmethod proceeds to step 535 where the cooling system remains on untilthe temperature H of the internal combustion engine 300 is less than thepredetermined temperature H2.

[0092] If the temperature H is less than or equal to the predeterminedtemperature H2, the control method proceeds to step S540 where the PLC210 shuts off the fuel supplied to the internal combustion engine 300.The internal combustion engine 300 remains on after the fuel is shutofffrom the internal combustion engine 300 because the remaining fuel andfuel vapors within the internal combustion engine 300 is burned off.Thus, the fuel within the fuel lines and manifolds is removed to preventbackfires and so that unburnt fuel and emissions are emitted.

[0093] The control method then proceeds to step S550 where the MCP 220receives an input from a sensor to determine if the internal combustionengine 300 has stopped. As should be appreciated, the internalcombustion engine 300 stops after the fuel and fuel vapors within theinternal combustion 300 are burned off. If the MCP 220 determines thatthe internal combustion engine 300 has stopped (S550:Yes), the controlmethod proceeds to step S560 where the PLC 210 turns off the ignitionspark of the internal combustion engine 300.

[0094] The control method then proceeds to step S570, where thetemperature H of the internal combustion engine, as determined by asensor, is compared to a predetermined temperature H3. The predeterminedtemperature H3 is lower than the predetermined temperature H2 and isused to uniformly cool the vehicle 10. The predetermined temperature H3is also used to prevent heat from releasing to the atmosphere and toprevent the heat soak after the internal combustion engine 300 has beenturned off.

[0095] If the temperature H of the internal combustion engine 300 ismore than the predetermined temperature H3 (S270:Yes), the controlmethod proceeds to step S575 where the cooling systems remain on.

[0096] When the MCP 220 receives input from the sensors indicating thatthe temperature H of the internal combustion engine 300 is less than orequal to the predetermined temperature H3, (S570:No), the control methodthen proceeds to step S580 where the PLC 210 turns off the coolingsystems. The control method then proceeds to step S250 where the controlmethod ends.

[0097] In various exemplary embodiments, the MCP 220 can increase therotation of the internal combustion engine 300 to increase the thermaloutput of the internal combustion engine 300. The increased thermaloutput can be used to increase the temperature within the cabin of thevehicle 10. Thus, the increased thermal output of the internalcombustion engine 300 can be used to warm the cabin of the vehicle 10during cold days or any other time where it is desired to increase thetemperature of the cabin of the vehicle 10. As should be appreciated,the internal combustion engine 300 can increase the rotation withoutincreasing the power generated as the IGBT 330 controls the conversionof AC voltage to DC voltage from the generator 310 as described above.

[0098] In various exemplary embodiments, the vehicle 10 can also usemore than one genset 300, 310. The additional genset 300, 310 can beused to generate additional energy or thermal output based on the sizeof the bus, the number of passengers on the bus, different routes usedby the vehicle 10, different energy requirements based on the time ofday, or any other situation which result in a high energy or thermaloutput, and thus a high variable genset 300, 310 output. The additionalgenset 300, 310 could be used only when the first genset 300, 310 is notable to maintain the charge of the battery array 30 or thermal output.The additional genset 300, 310 can also be used equally with the firstgenset 300, 310. Furthermore, the first or additional genset 300, 310can be smaller and thus have a smaller output than the other genset 300,310. However, it should be appreciated that any other use of theadditional genset 300, 310 can be used to supplement the first genset300, 310.

[0099] While the invention has been described with reference to variousexemplary embodiments thereof, it is to be understood that the inventionis not limited to the disclosed embodiments or constructions. To thecontrary, the invention is intended to cover various modifications andequivalent arrangements. In addition, while the various elements of thedisclosed invention are shown in various combinations andconfigurations, which are exemplary, other combinations andconfigurations, including more, less or only a single element, are alsowithin the spirit and scope of the invention.

[0100] In addition, this invention covers apparatus and methods tocontrol the vehicle through various emission modes. Moreover, thisinvention also covers circumstances where a transition period is usedbefore entering the zero emission mode. Thus the transition period forturning off the internal combustion engine can be used before enteringthe zero emission zone to prevents emission from entering the zeroemission zone. Also, as stated, the subject apparatus and method can beutilized by manual activation, as opposed to the use of automatic switchmechanisms.

What is claimed is:
 1. A method for adaptively controlling a series typehybrid electric vehicle including an internal combustion engineconnected to a generator and at least one electric motor with the engineand generator selectively operated in various operation modes,comprising: operating the vehicle in a first mode in which internalcombustion engine and generator are off and the motor propels thevehicle from power stored in the battery array; operating the vehicle ina second mode in which the internal combustion engine and generator areoperating without restriction; and operating the vehicle in a third modein which the operation of the internal combustion engine and generatorare at least partially restricted to limit vehicle discharges.
 2. Themethod of claim 1, further comprising: operating the vehicle in thefirst mode when the vehicle is driven in a zone where substantially zeroemissions are allowed.
 3. The method of claim 1, further comprising:operating the vehicle in the second mode when the vehicle is driven in azone with substantially no emission restrictions.
 4. The method of claim1, further comprising: operating a vehicle in a third mode when thevehicle is driven in a zone with emission restrictions.
 5. The method ofclaim 1, further comprising: operating the generator as a motor to startthe internal combustion engine.
 6. The method of claim 1, furthercomprising: operating an oil pump to raise the oil pressure of theengine when the engine is off and immediately before the engine isstarted.
 7. The method of claim 6, when the pump is integral with thegenerator.
 8. The method of claim 1, further comprising: applying anignition spark in the engine after a predetermined oil pressure isobtained in the internal combustion engine when starting the engine. 9.The method of claim 8, further comprising: supplying fuel to theinternal combustion engine after an ignition spark has been applied. 10.The method of claim 1, further comprising: operating the generator as amotor to start the internal combustion engine; and removing thegenerator as a motor to start the internal combustion engine after theinternal combustion engine has reached a predetermined rotation.
 11. Themethod of claim 1, further comprising: raising the temperature of theinternal combustion engine before turning on the internal combustionengine.
 12. The method of claim 11, wherein the temperature of theinternal combustion engine is raised while in an idle mode.
 13. Themethod of claim 1, further comprising: determining if the internalcombustion engine and generator have exceeded a predetermined energylevel while operating in the second and third modes; and lowering anenergy level of the internal combustion engine and generator if thepredetermined energy level has been exceed.
 14. The method of claim 13,wherein the energy level is lowered by reducing a rotation of theinternal combustion engine.
 15. The method of claim 13, wherein theenergy level is lowered by applying a retarder to the internalcombustion engine.
 16. The method of claim 1, further comprising:allowing the engine to idle after a fuel supply has stopped the engineto deplete any unburned fuel and combustible gases from the engine. 17.The method of claim 1, further comprising: activating a cooling systemto lower the temperature of the internal combustion engine to apredetermined temperature before turning off the engine.
 18. The methodof claim 17, further comprising: shutting off a fuel supplied to theinternal combustion engine after the internal combustion engine is belowthe predetermined temperature level when turning off the engine.
 19. Aseries type hybrid electric vehicle, comprising: an internal combustionengine connected to a generator; a battery array receiving current atleast from the generator; a least one electric motor receiving currentfrom the battery array, the motor propelling the vehicle; and acontroller that selectively operates the engine and generator in variousoperating modes, including: a first mode in which the internalcombustion engine and generator are off and the motor propels thevehicle from power stored in the battery array; a second mode in whichthe internal combustion engine and generator are operating withoutrestriction; and a third mode in which the operation of the internalcombustion engine and generator are at least partially restricted tolimit vehicle discharges.
 20. The vehicle of claim 19, wherein thecontroller: operates the vehicle in the first mode when the vehicle isdriven in a zone where substantially zero emissions are allowed.
 21. Thevehicle of claim 19, wherein the controller: operates the vehicle in thesecond mode when the vehicle is driven in a zone with substantially noemission restrictions.
 22. The vehicle of claim 19, wherein thecontroller: operates the vehicle in a third mode when the vehicle isdriven in a zone with emission restrictions.
 23. The vehicle of claim19, wherein the controller: operates the generator as a motor to startthe internal combustion engine.
 24. The vehicle of claim 19, furthercomprising: an oil pump selectively operated to raise oil pressure ofthe engine when the engine is off and immediately before the engine isstarted.
 25. The vehicle of claim 24, wherein the pump is integral withthe generator.
 26. The vehicle of claim 19, wherein an ignition spark isapplied after a predetermined oil pressure is obtained in the internalcombustion engine when starting the engine.
 27. The vehicle of claim 26,wherein fuel is supplied to the internal combustion engine after anignition spark has been applied.
 28. The vehicle of claim 19, whereinthe controller: operates the generator as a motor to start the internalcombustion engine; and removes the generator as a motor to start theinternal combustion engine after the internal combustion engine hasreached a predetermined rotation.
 29. The vehicle of claim 19, whereinthe temperature of the internal combustion engine is raised beforeturning on the internal combustion engine.
 30. The vehicle of claim 29,wherein the temperature of the internal combustion engine is raisedwhile in an idle mode.
 31. The vehicle of claim 19, wherein thecontroller: determines if the internal combustion engine and generatorhave exceeded a predetermined energy level while operating in the secondand third modes; and lowers an energy level of the internal combustionengine and generator if the predetermined energy level has beenexceeded.
 32. The vehicle of claim 31, wherein the energy level islowered by reducing a rotation of the internal combustion engine. 33.The vehicle of claim 31, wherein the energy level is lowered by applyinga retarder to the internal combustion engine.
 34. The vehicle of claim19, wherein the controller: allows the engine to idle after a fuelsupply has stopped the engine to deplete any unburned fuel andcombustible gases from the engine.
 35. The vehicle of claim 19, whereinthe controller: activates a cooling system to lower the temperature ofthe internal combustion engine to a predetermined temperature beforeturning off the engine.
 36. The vehicle of claim 35, wherein thecontroller: turns off the fuel supplied to the internal combustionengine after the internal combustion engine is below the predeterminedtemperature level when turning off the temperature.